HealthTraining & Performance
Sweat Science

How to Make Your Strength Routine Evidence-Based

New research hands down verdicts on what to lift, how much, and how hard

The biggest difference of all is between doing nothing and doing something. (Photo: Sergio Marcos/Stocksy)
Men Exercising With Barbells In A Crossfit Box

As an endurance guy, I spend an embarrassing amount of time thinking about things like the work-rest ratio of my interval workouts and the extra energy required to run around corners. Meanwhile, my thoughts about strength training rarely extend beyond the vague sense that I should probably do some.

To remedy that imbalance, here’s a roundup of recent research that offers some useful takeaways about the what, when, and how of resistance training. (For the why, take a look at this previous article on the link between strength training and running efficiency.)

Seek Confusion

Or not—depends how you look at it. A recent study in PLOS One by a team led by Carlos Balsalobre-Fernández of the Autonomous University of Madrid looked at the concept of “muscle confusion.” The idea is that by constantly switching up the components of your workout, you’ll get better strength gains than if you just do the same exercises over and over again.

They tested this idea on 21 volunteers who did eight weeks of strength training either doing the same exercises (six upper-body and six lower-body) over and over, or doing a workout randomly drawn each day from a database of 80 different exercises. The workouts were matched for load and targeted muscles. And by the end of the program, there were no meaningful differences between groups (but, if anything, perhaps a hint of an advantage for the group doing the same exercises repeatedly).

On the other hand, the muscle-confusion group reported significantly greater motivation to keep exercising after the study. “The differences in motivation were pretty substantial,” co-author Brad Schoenfeld of Lehman College told the New York Times. In other words, don’t get too wound up about the details of your workout routine, but make sure you choose a regimen that you find engaging.

Don’t Fear Failure

Researchers have been debating two key muscle-related questions in recent years. One is whether you can gain as much muscle and strength with light weights as you can with heavy weights. The other is whether it’s necessary—or perhaps even counterproductive—to lift to failure in each set. Those two questions collide in a new study from researchers in São Paolo, Brazil (along with, once again, Schoenfeld), published in the Journal of Strength and Conditioning Research.

The study’s 25 volunteers completed an eight-week lower-body training program, which each subject randomized to two of four different routines (one for each leg):

  • light weights to failure
  • heavy weights to failure
  • light weights not to failure
  • heavy weights not to failure

The light weights were at 30 percent of one-rep max, while the heavy weights were at 80 percent. In the not-to-failure condition, the subjects averaged 19.6 reps per light set instead of 34.4 at failure, and 6.7 reps per heavy set instead of 12.4 at failure. Each workout involved three sets of knee extensions.

There are two outcomes of interest: strength and muscle size. For strength, both heavy-load groups gained about 33 percent, while both light-load groups gained about 16 to 17 percent. Going to failure didn’t make any significant difference, but heavier weights seemed to be better than light ones. To get strong, go heavy.

For muscle size, three of the groups gained around 8 percent in cross-sectional area. The exception was the light-weight, not-to-failure group, which gained only 2.8 percent. So if you’re looking to gain muscle size with light weights, you need to push it to failure (or at least somewhere close). With heavier weights, that doesn’t seem to matter.

Stop After One

From the tell-me-what-I-want-to-hear department, a study from—wait for it—Brad Schoenfeld’s group at Lehman College. This one was actually published a year ago in Medicine & Science in Sports & Exercise, but it tackles a crucial question and is worth revisiting.

Schoenfeld and his colleagues split 34 volunteers into three groups who once again underwent eight weeks of thrice-weekly training sessions, doing seven exercises per session. One group did a single set of each exercise, with the weight chosen to produce failure within 8 to 12 reps. The second group did three sets, all to failure. The third group did five sets, with the weight adjusted as needed to keep hitting failure between 8 and 12 reps. As Schoenfeld pointed out in an interview when the study was released, that means the groups were spending a total of either 13, 40, or 70 minutes per session—a big difference.

The results: everyone got substantially stronger, with no significant differences between groups. A single set—but a hard one—was enough to get most of the available gains. For muscle size, everyone got bigger, but in this case doing more sets did translate into bigger gains.


Put all these results together, shake them around, and you emerge with some fairly simple guidelines for people who want to get stronger but aren’t planning to enter any bodybuilding competitions. Pick a range of exercises covering the body’s major muscle groups (here’s a good place to start, courtesy of Brad Stulberg). Do at least one set of each, several times a week, aiming for about 8 to 12 reps, and be consistent about your routine. If you use lighter weights, push close to failure on each set. To maximize size gains, do more sets.

And maybe the most important takeaway of all: every single group in every one of these studies got bigger and stronger. Sure, the details make a difference. But the biggest difference of all is between doing nothing and doing something. 


For more Sweat Science, join me on Twitter and Facebook, sign up for the email newsletter, and check out my book Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance.

Our mission to inspire readers to get outside has never been more critical. In recent years, Outside Online has reported on groundbreaking research linking time in nature to improved mental and physical health, and we’ve kept you informed about the unprecedented threats to America’s public lands. Our rigorous coverage helps spark important debates about wellness and travel and adventure, and it provides readers an accessible gateway to new outdoor passions. Time outside is essential—and we can help you make the most of it. Making a financial contribution to Outside Online only takes a few minutes and will ensure we can continue supplying the trailblazing, informative journalism that readers like you depend on. We hope you’ll support us. Thank you.
Contribute to Outside
Filed To: ScienceWorkoutsStrength and Power Training
Lead Photo: Sergio Marcos/Stocksy

When you buy something using the retail links in our stories, we may earn a small commission. Outside does not accept money for editorial gear reviews. Read more about our policy.

More Health